We will study the value of using creatine kinase isozyme BB (CK-BB) as a marker for various cancer types. Serum and effusion activity and concentration of CK-BB will be measured in patients with various malignancies and non-malignant conditions. Correlations will be performed between CK-BB levels and clinical stage of disease. The role of CK-BB in monitoring patients receiving chemotherapy for response or disease progression will be evaluated. The role of CK-BB in the diagnosis of malignant diseases will be explored. The usefulness of simultaneous CEA and CK-BB assays will also be investigated. The cellular source of the circulating CK-BB in cancer patients will be established by immunohistology of various tissues. Serum and effusion analysis of CK-BB wil be performed using conventional enzymatic electrophoresis and a specific radioimmunoassay for brain CK-BB. CK-BB from malignant breast effusions will be purified and used to develop a new radioimmunoassay for CK-BB derived from glandular epithelium. The new radioimmunoassay will be compared with the current one for effectiveness in detecting malignant disease. The prevalence, nature and specificity of immunoglobulins in sera of cancer patients which bind CK-BB will also be investigated. Results of studies should evaluate the utility of CK-BB as a tumor marker.